A pair of colliding galaxies called NGC 6240 in a rare, short-lived phase of their evolution just before they merge into a single, larger galaxy.

The prolonged, violent collision drastically altered the appearance of both galaxies and created huge amounts of heat turning NGC 6240 into an "infrared luminous" active galaxy.

Photo created from combined data from the infrared array camera of NASA's Spitzer Space Telescope. NASA/JPL/AP